Maker Factory ELECTRONICS EXPERIMENTS BOX Manual page 100

Circuit 77: LC low pass 3.4 kHz
Setup information
Install the fixed value inductor and the electrolytic capacitor as shown in Fig. 2.77. Then connect the Piezo
element. Check the placement on the board again. You can significantly increase the sensitivity of the Piezo
element by using a sound plate or even a sound box. Read more about it in Chap. 1.2.3
Experiment
We will use electrical filter circuits, among other things, to suppress the noise. A basic circuit that serves
this purpose is a RC or LC filter consisting of a resistor/inductor and a capacitor Depending on the wiring,
this creates a low pass or a high pass. In our case, we are using an LC low pass filter. The cut-off frequency,
up to which signals can pass, is 3.4 kHz If you have an mp3 player connected to the input, it will sound as if
the music comes from a handset.
The circuit diagram for this experiment is shown in Chap. 3, Fig. 3.77.
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Components required:
1 x 220 μH fixed induct-
ance, 1 x 10 μF electro-
lytic capacitor, 1 x Piezo
element, 1 x breadboard
Fig. 2.77: LC high pass from
on 3.4 kHz